Because liberals project alot!
Your problem is the evidence.
Evidence like show us a high profile liberal that supports creationism.
Well, I definitely know of many liberals (actually, this is a cornerstone of the liberal mindset) who reject evolution, its principles and implications. Just ask James Watson (the ‘double helix’ guy, who got busted for suggesting that different groups of people may have evolved separately, to a different outcome with respect to IQ; his liberal opponents, on the other hand, seem to believe that humans were created ‘according to their kind’, in a biblical manner).